Naphthol or phenol couplers are generally used for the formation of a cyan dye image. However, these couplers commonly have a major disadvantage in that color reproduction is very poor since they have undesirable absorptions in the short wavelength regions (in the region from green to blue). The resolution of this problem is desirable.
On the other hand, the couplers disclosed in JP-A-63-141057 are similar to the coupler of the present invention but they are magenta couplers. (The term "JP-A" as disclosed herein signifies an "unexamined published Japanese patent application".) Although, as magenta couplers, they certainly are improved in terms of color image fastness and color reproduction, there is the major problem of hue modification when they are used as cyan couplers. Moreover, a more active coupling reaction with the oxidized product of a primary aromatic amine color developing agent is also required.
Furthermore, pyrrolopyrazole type couplers have been disclosed in European Patent 456,226A with a view to improving the hue of the cyan dye image and improving color reproduction. Although the couplers disclosed in that specification have somewhat improved color forming properties (a high coupling reactivity with the oxidized product of a color developing agent and a high molecular extinction coefficient for the dye which is formed), improved colored image fastness and improved hue of the color forming dye, further improvement is desirable. Moreover, improvement is needed in terms of picture quality such as color reproduction and sharpness and in terms of processing stability during color development.
On the other hand, there is a need with color photosensitive materials, and especially with camera color sensitive materials, for good picture quality at high photographic speed and for stable color development processing.
The use of tabular silver halide grains for which the ratio of the diameter and the thickness (the aspect ratio) is at least 8:1 has been proposed, for example, in JP-A-58-113934 (corresponding to U.S. Pat. No. 4,439,520) as a means of providing color photosensitive materials which have such excellent picture quality at high photographic speeds. But this is still unsatisfactory in terms of increased photographic speeds, picture quality, sensitive material storage properties and color development processing stability, and still further improvement is required.